Quantum computers make direct use of quantum-mechanical phenomena, such as superposition, tunnelling and entanglement, to perform operations on data.
If all the world had were sticks and stones, the guy with the machine gun would reign supreme.
That's essentially the situation with the arrival of quantum computers. They are so powerful that it takes mere hours to solve problems that would take modern computers years to work through. That means the moment the first quantum computer turns on, encrypted data across the internet becomes 'see through'.
Encryption is the process of encoding a message or information such that only authorized parties can access it. Encryption does not prevent interference, but it denied intelligible content to a would-be interceptor.To encrypt something, you need a cipher which is an algorithm that conerts the message into a scrambled mess of characters that can only be turned baack into the original mesage using a special key.
When you see that padlock on a shopping or bank site, or when you use Skype for video chats, or mail servers and a host of others, your communication is encrypted. If someone breaks that encryption, your details - such as your credit card, address, and what you are buying, are theirs to own.
Modern computers use "public-key encryption", which rely on the fact that it is much harder to figure out the factors of a number than to multiply them to make a number. Quick,what two numbers do you multiply together to produce 323? If you choose two large prime numbers, a computer can easily multiply them together, but it cannot deconstruct the result with anything like the same ease. The key to public-key encryption is thus to generate large numbers that only you(or your computer) know. The large number can be published online, and used to encrypt a mrssage using specific and well-tested formulae.
In the real world, the difficult math problems that public key rely on are called hidden subgroup problems.
o here's the thing, experts predict that once quantum computers are up and running,they'll be able to solve hidden subgroup problems in no time. That is because while traditional computers manipulate every particle or "bit" of information as either a 0 or 1, quantum bits or "qbits" can exist as 0, 1 and all other points in between. That makes quantum computers millions of times more powerful than the computers that created those encryption algorithms.
Nobody has created a quantum computer that can do anything of real importance yet, but it is reasonable to assume they'll be here around 2025. And like any technology, we won't swith from traditional to quantum computing in one full sweep - it will be gradual and that leaves traditional cryptography at risk. Even secure information from the past is at risk. An attacker can record our secure communication today and break it years later. "All of today's secrets will be lost" warns Tanja Lange, professor of cryptology at Eindhoven University of Technology.
But there's hope. Lange leads the research consortium on Post-Quantum Cryptography, PQCrypto, which combines the intellectual prowess of 11 different universities and companies to come up with new ways of encrypting data, hopefully without the use of hidden subgroup problems. It only started in 2015 and Lange says it can take up to 20 years after development for a new cryptographic technique to reach the end user. But they may have no other choice.